Steady reynolds averaged navier stokes equation-based buffet loads estimation

A method to estimate buffet loads on lifting surfaces immersed in turbulent streams using steady Reynolds Averaged Navier Stokes (RANS) equation solutions is presented. A generalization of a model developed by Liepmann based on thin airfoil theory and statistical concepts is employed. Mean flow and turbulence-derived quantities required by the method are supplied by steady RANS equation model data. The SST turbulence model is used here. The predictive capability of the method is assessed by comparison to unsteady turbulence simulation results. A half-step is also taken wherein turbulence simulation results are used to close the Liepmann model allowing that models performance to be isolated from that of the RANS model. The E-2D Advanced Hawkeye rotodome exposed to a compressible turbulent plume is used as a test case. The half-step results show that the Liepmann model itself performs well when both the upper and lower surfaces of the rotodome are within the stream. This is consistent with the models use of a fluctuating angle of attack. Estimates obtained using steady RANS equation-based results within the Liepmann model are not as favorable due to mean flow prediction differences. But they are reasonable and have been found to be useful in an environment where a large number of cases need to be quickly analyzed.